Viewing file:  primnodes.h (56.6 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*-------------------------------------------------------------------------
*
* primnodes.h
* Definitions for "primitive" node types, those that are used in more
* than one of the parse/plan/execute stages of the query pipeline.
* Currently, these are mostly nodes for executable expressions
* and join trees.
*
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/nodes/primnodes.h
*
*-------------------------------------------------------------------------
*/
#ifndef PRIMNODES_H
#define PRIMNODES_H
#include "access/attnum.h"
#include "nodes/pg_list.h"
/* ----------------------------------------------------------------
* node definitions
* ----------------------------------------------------------------
*/
/*
* Alias -
* specifies an alias for a range variable; the alias might also
* specify renaming of columns within the table.
*
* Note: colnames is a list of Value nodes (always strings). In Alias structs
* associated with RTEs, there may be entries corresponding to dropped
* columns; these are normally empty strings (""). See parsenodes.h for info.
*/
typedef struct Alias
{
NodeTag type;
char *aliasname; /* aliased rel name (never qualified) */
List *colnames; /* optional list of column aliases */
} Alias;
typedef enum InhOption
{
INH_NO, /* Do NOT scan child tables */
INH_YES, /* DO scan child tables */
INH_DEFAULT /* Use current SQL_inheritance option */
} InhOption;
/* What to do at commit time for temporary relations */
typedef enum OnCommitAction
{
ONCOMMIT_NOOP, /* No ON COMMIT clause (do nothing) */
ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */
ONCOMMIT_DELETE_ROWS, /* ON COMMIT DELETE ROWS */
ONCOMMIT_DROP /* ON COMMIT DROP */
} OnCommitAction;
/*
* RangeVar - range variable, used in FROM clauses
*
* Also used to represent table names in utility statements; there, the alias
* field is not used, and inhOpt shows whether to apply the operation
* recursively to child tables. In some contexts it is also useful to carry
* a TEMP table indication here.
*/
typedef struct RangeVar
{
NodeTag type;
char *catalogname; /* the catalog (database) name, or NULL */
char *schemaname; /* the schema name, or NULL */
char *relname; /* the relation/sequence name */
InhOption inhOpt; /* expand rel by inheritance? recursively act
* on children? */
char relpersistence; /* see RELPERSISTENCE_* in pg_class.h */
Alias *alias; /* table alias & optional column aliases */
int location; /* token location, or -1 if unknown */
} RangeVar;
/*
* IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
* CREATE MATERIALIZED VIEW
*
* For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten
* SELECT Query for the view; otherwise it's NULL. (Although it's actually
* Query*, we declare it as Node* to avoid a forward reference.)
*/
typedef struct IntoClause
{
NodeTag type;
RangeVar *rel; /* target relation name */
List *colNames; /* column names to assign, or NIL */
List *options; /* options from WITH clause */
OnCommitAction onCommit; /* what do we do at COMMIT? */
char *tableSpaceName; /* table space to use, or NULL */
Node *viewQuery; /* materialized view's SELECT query */
bool skipData; /* true for WITH NO DATA */
} IntoClause;
/* ----------------------------------------------------------------
* node types for executable expressions
* ----------------------------------------------------------------
*/
/*
* Expr - generic superclass for executable-expression nodes
*
* All node types that are used in executable expression trees should derive
* from Expr (that is, have Expr as their first field). Since Expr only
* contains NodeTag, this is a formality, but it is an easy form of
* documentation. See also the ExprState node types in execnodes.h.
*/
typedef struct Expr
{
NodeTag type;
} Expr;
/*
* Var - expression node representing a variable (ie, a table column)
*
* Note: during parsing/planning, varnoold/varoattno are always just copies
* of varno/varattno. At the tail end of planning, Var nodes appearing in
* upper-level plan nodes are reassigned to point to the outputs of their
* subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR
* and varattno becomes the index of the proper element of that subplan's
* target list. Similarly, INDEX_VAR is used to identify Vars that reference
* an index column rather than a heap column. (In ForeignScan and CustomScan
* plan nodes, INDEX_VAR is abused to signify references to columns of a
* custom scan tuple type.) In all these cases, varnoold/varoattno hold the
* original values. The code doesn't really need varnoold/varoattno, but they
* are very useful for debugging and interpreting completed plans, so we keep
* them around.
*/
#define INNER_VAR 65000 /* reference to inner subplan */
#define OUTER_VAR 65001 /* reference to outer subplan */
#define INDEX_VAR 65002 /* reference to index column */
#define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR)
/* Symbols for the indexes of the special RTE entries in rules */
#define PRS2_OLD_VARNO 1
#define PRS2_NEW_VARNO 2
typedef struct Var
{
Expr xpr;
Index varno; /* index of this var's relation in the range
* table, or INNER_VAR/OUTER_VAR/INDEX_VAR */
AttrNumber varattno; /* attribute number of this var, or zero for
* all */
Oid vartype; /* pg_type OID for the type of this var */
int32 vartypmod; /* pg_attribute typmod value */
Oid varcollid; /* OID of collation, or InvalidOid if none */
Index varlevelsup; /* for subquery variables referencing outer
* relations; 0 in a normal var, >0 means N
* levels up */
Index varnoold; /* original value of varno, for debugging */
AttrNumber varoattno; /* original value of varattno */
int location; /* token location, or -1 if unknown */
} Var;
/*
* Const
*
* Note: for varlena data types, we make a rule that a Const node's value
* must be in non-extended form (4-byte header, no compression or external
* references). This ensures that the Const node is self-contained and makes
* it more likely that equal() will see logically identical values as equal.
*/
typedef struct Const
{
Expr xpr;
Oid consttype; /* pg_type OID of the constant's datatype */
int32 consttypmod; /* typmod value, if any */
Oid constcollid; /* OID of collation, or InvalidOid if none */
int constlen; /* typlen of the constant's datatype */
Datum constvalue; /* the constant's value */
bool constisnull; /* whether the constant is null (if true,
* constvalue is undefined) */
bool constbyval; /* whether this datatype is passed by value.
* If true, then all the information is stored
* in the Datum. If false, then the Datum
* contains a pointer to the information. */
int location; /* token location, or -1 if unknown */
} Const;
/*
* Param
*
* paramkind specifies the kind of parameter. The possible values
* for this field are:
*
* PARAM_EXTERN: The parameter value is supplied from outside the plan.
* Such parameters are numbered from 1 to n.
*
* PARAM_EXEC: The parameter is an internal executor parameter, used
* for passing values into and out of sub-queries or from
* nestloop joins to their inner scans.
* For historical reasons, such parameters are numbered from 0.
* These numbers are independent of PARAM_EXTERN numbers.
*
* PARAM_SUBLINK: The parameter represents an output column of a SubLink
* node's sub-select. The column number is contained in the
* `paramid' field. (This type of Param is converted to
* PARAM_EXEC during planning.)
*
* PARAM_MULTIEXPR: Like PARAM_SUBLINK, the parameter represents an
* output column of a SubLink node's sub-select, but here, the
* SubLink is always a MULTIEXPR SubLink. The high-order 16 bits
* of the `paramid' field contain the SubLink's subLinkId, and
* the low-order 16 bits contain the column number. (This type
* of Param is also converted to PARAM_EXEC during planning.)
*/
typedef enum ParamKind
{
PARAM_EXTERN,
PARAM_EXEC,
PARAM_SUBLINK,
PARAM_MULTIEXPR
} ParamKind;
typedef struct Param
{
Expr xpr;
ParamKind paramkind; /* kind of parameter. See above */
int paramid; /* numeric ID for parameter */
Oid paramtype; /* pg_type OID of parameter's datatype */
int32 paramtypmod; /* typmod value, if known */
Oid paramcollid; /* OID of collation, or InvalidOid if none */
int location; /* token location, or -1 if unknown */
} Param;
/*
* Aggref
*
* The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes.
*
* For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries
* represent the aggregate's regular arguments (if any) and resjunk TLEs can
* be added at the end to represent ORDER BY expressions that are not also
* arguments. As in a top-level Query, the TLEs can be marked with
* ressortgroupref indexes to let them be referenced by SortGroupClause
* entries in the aggorder and/or aggdistinct lists. This represents ORDER BY
* and DISTINCT operations to be applied to the aggregate input rows before
* they are passed to the transition function. The grammar only allows a
* simple "DISTINCT" specifier for the arguments, but we use the full
* query-level representation to allow more code sharing.
*
* For an ordered-set aggregate, the args list represents the WITHIN GROUP
* (aggregated) arguments, all of which will be listed in the aggorder list.
* DISTINCT is not supported in this case, so aggdistinct will be NIL.
* The direct arguments appear in aggdirectargs (as a list of plain
* expressions, not TargetEntry nodes).
*
* aggtranstype is the data type of the state transition values for this
* aggregate (resolved to an actual type, if agg's transtype is polymorphic).
* This is determined during planning and is InvalidOid before that.
*
* aggargtypes is an OID list of the data types of the direct and regular
* arguments. Normally it's redundant with the aggdirectargs and args lists,
* but in a combining aggregate, it's not because the args list has been
* replaced with a single argument representing the partial-aggregate
* transition values.
*
* aggsplit indicates the expected partial-aggregation mode for the Aggref's
* parent plan node. It's always set to AGGSPLIT_SIMPLE in the parser, but
* the planner might change it to something else. We use this mainly as
* a crosscheck that the Aggrefs match the plan; but note that when aggsplit
* indicates a non-final mode, aggtype reflects the transition data type
* not the SQL-level output type of the aggregate.
*/
typedef struct Aggref
{
Expr xpr;
Oid aggfnoid; /* pg_proc Oid of the aggregate */
Oid aggtype; /* type Oid of result of the aggregate */
Oid aggcollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that function should use */
Oid aggtranstype; /* type Oid of aggregate's transition value */
List *aggargtypes; /* type Oids of direct and aggregated args */
List *aggdirectargs; /* direct arguments, if an ordered-set agg */
List *args; /* aggregated arguments and sort expressions */
List *aggorder; /* ORDER BY (list of SortGroupClause) */
List *aggdistinct; /* DISTINCT (list of SortGroupClause) */
Expr *aggfilter; /* FILTER expression, if any */
bool aggstar; /* TRUE if argument list was really '*' */
bool aggvariadic; /* true if variadic arguments have been
* combined into an array last argument */
char aggkind; /* aggregate kind (see pg_aggregate.h) */
Index agglevelsup; /* > 0 if agg belongs to outer query */
AggSplit aggsplit; /* expected agg-splitting mode of parent Agg */
int location; /* token location, or -1 if unknown */
} Aggref;
/*
* GroupingFunc
*
* A GroupingFunc is a GROUPING(...) expression, which behaves in many ways
* like an aggregate function (e.g. it "belongs" to a specific query level,
* which might not be the one immediately containing it), but also differs in
* an important respect: it never evaluates its arguments, they merely
* designate expressions from the GROUP BY clause of the query level to which
* it belongs.
*
* The spec defines the evaluation of GROUPING() purely by syntactic
* replacement, but we make it a real expression for optimization purposes so
* that one Agg node can handle multiple grouping sets at once. Evaluating the
* result only needs the column positions to check against the grouping set
* being projected. However, for EXPLAIN to produce meaningful output, we have
* to keep the original expressions around, since expression deparse does not
* give us any feasible way to get at the GROUP BY clause.
*
* Also, we treat two GroupingFunc nodes as equal if they have equal arguments
* lists and agglevelsup, without comparing the refs and cols annotations.
*
* In raw parse output we have only the args list; parse analysis fills in the
* refs list, and the planner fills in the cols list.
*/
typedef struct GroupingFunc
{
Expr xpr;
List *args; /* arguments, not evaluated but kept for
* benefit of EXPLAIN etc. */
List *refs; /* ressortgrouprefs of arguments */
List *cols; /* actual column positions set by planner */
Index agglevelsup; /* same as Aggref.agglevelsup */
int location; /* token location */
} GroupingFunc;
/*
* WindowFunc
*/
typedef struct WindowFunc
{
Expr xpr;
Oid winfnoid; /* pg_proc Oid of the function */
Oid wintype; /* type Oid of result of the window function */
Oid wincollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that function should use */
List *args; /* arguments to the window function */
Expr *aggfilter; /* FILTER expression, if any */
Index winref; /* index of associated WindowClause */
bool winstar; /* TRUE if argument list was really '*' */
bool winagg; /* is function a simple aggregate? */
int location; /* token location, or -1 if unknown */
} WindowFunc;
/* ----------------
* ArrayRef: describes an array subscripting operation
*
* An ArrayRef can describe fetching a single element from an array,
* fetching a subarray (array slice), storing a single element into
* an array, or storing a slice. The "store" cases work with an
* initial array value and a source value that is inserted into the
* appropriate part of the array; the result of the operation is an
* entire new modified array value.
*
* If reflowerindexpr = NIL, then we are fetching or storing a single array
* element at the subscripts given by refupperindexpr. Otherwise we are
* fetching or storing an array slice, that is a rectangular subarray
* with lower and upper bounds given by the index expressions.
* reflowerindexpr must be the same length as refupperindexpr when it
* is not NIL.
*
* In the slice case, individual expressions in the subscript lists can be
* NULL, meaning "substitute the array's current lower or upper bound".
*
* Note: the result datatype is the element type when fetching a single
* element; but it is the array type when doing subarray fetch or either
* type of store.
*
* Note: for the cases where an array is returned, if refexpr yields a R/W
* expanded array, then the implementation is allowed to modify that object
* in-place and return the same object.)
* ----------------
*/
typedef struct ArrayRef
{
Expr xpr;
Oid refarraytype; /* type of the array proper */
Oid refelemtype; /* type of the array elements */
int32 reftypmod; /* typmod of the array (and elements too) */
Oid refcollid; /* OID of collation, or InvalidOid if none */
List *refupperindexpr;/* expressions that evaluate to upper array
* indexes */
List *reflowerindexpr;/* expressions that evaluate to lower array
* indexes, or NIL for single array element */
Expr *refexpr; /* the expression that evaluates to an array
* value */
Expr *refassgnexpr; /* expression for the source value, or NULL if
* fetch */
} ArrayRef;
/*
* CoercionContext - distinguishes the allowed set of type casts
*
* NB: ordering of the alternatives is significant; later (larger) values
* allow more casts than earlier ones.
*/
typedef enum CoercionContext
{
COERCION_IMPLICIT, /* coercion in context of expression */
COERCION_ASSIGNMENT, /* coercion in context of assignment */
COERCION_EXPLICIT /* explicit cast operation */
} CoercionContext;
/*
* CoercionForm - how to display a node that could have come from a cast
*
* NB: equal() ignores CoercionForm fields, therefore this *must* not carry
* any semantically significant information. We need that behavior so that
* the planner will consider equivalent implicit and explicit casts to be
* equivalent. In cases where those actually behave differently, the coercion
* function's arguments will be different.
*/
typedef enum CoercionForm
{
COERCE_EXPLICIT_CALL, /* display as a function call */
COERCE_EXPLICIT_CAST, /* display as an explicit cast */
COERCE_IMPLICIT_CAST /* implicit cast, so hide it */
} CoercionForm;
/*
* FuncExpr - expression node for a function call
*/
typedef struct FuncExpr
{
Expr xpr;
Oid funcid; /* PG_PROC OID of the function */
Oid funcresulttype; /* PG_TYPE OID of result value */
bool funcretset; /* true if function returns set */
bool funcvariadic; /* true if variadic arguments have been
* combined into an array last argument */
CoercionForm funcformat; /* how to display this function call */
Oid funccollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that function should use */
List *args; /* arguments to the function */
int location; /* token location, or -1 if unknown */
} FuncExpr;
/*
* NamedArgExpr - a named argument of a function
*
* This node type can only appear in the args list of a FuncCall or FuncExpr
* node. We support pure positional call notation (no named arguments),
* named notation (all arguments are named), and mixed notation (unnamed
* arguments followed by named ones).
*
* Parse analysis sets argnumber to the positional index of the argument,
* but doesn't rearrange the argument list.
*
* The planner will convert argument lists to pure positional notation
* during expression preprocessing, so execution never sees a NamedArgExpr.
*/
typedef struct NamedArgExpr
{
Expr xpr;
Expr *arg; /* the argument expression */
char *name; /* the name */
int argnumber; /* argument's number in positional notation */
int location; /* argument name location, or -1 if unknown */
} NamedArgExpr;
/*
* OpExpr - expression node for an operator invocation
*
* Semantically, this is essentially the same as a function call.
*
* Note that opfuncid is not necessarily filled in immediately on creation
* of the node. The planner makes sure it is valid before passing the node
* tree to the executor, but during parsing/planning opfuncid can be 0.
*/
typedef struct OpExpr
{
Expr xpr;
Oid opno; /* PG_OPERATOR OID of the operator */
Oid opfuncid; /* PG_PROC OID of underlying function */
Oid opresulttype; /* PG_TYPE OID of result value */
bool opretset; /* true if operator returns set */
Oid opcollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that operator should use */
List *args; /* arguments to the operator (1 or 2) */
int location; /* token location, or -1 if unknown */
} OpExpr;
/*
* DistinctExpr - expression node for "x IS DISTINCT FROM y"
*
* Except for the nodetag, this is represented identically to an OpExpr
* referencing the "=" operator for x and y.
* We use "=", not the more obvious "<>", because more datatypes have "="
* than "<>". This means the executor must invert the operator result.
* Note that the operator function won't be called at all if either input
* is NULL, since then the result can be determined directly.
*/
typedef OpExpr DistinctExpr;
/*
* NullIfExpr - a NULLIF expression
*
* Like DistinctExpr, this is represented the same as an OpExpr referencing
* the "=" operator for x and y.
*/
typedef OpExpr NullIfExpr;
/*
* ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
*
* The operator must yield boolean. It is applied to the left operand
* and each element of the righthand array, and the results are combined
* with OR or AND (for ANY or ALL respectively). The node representation
* is almost the same as for the underlying operator, but we need a useOr
* flag to remember whether it's ANY or ALL, and we don't have to store
* the result type (or the collation) because it must be boolean.
*/
typedef struct ScalarArrayOpExpr
{
Expr xpr;
Oid opno; /* PG_OPERATOR OID of the operator */
Oid opfuncid; /* PG_PROC OID of underlying function */
bool useOr; /* true for ANY, false for ALL */
Oid inputcollid; /* OID of collation that operator should use */
List *args; /* the scalar and array operands */
int location; /* token location, or -1 if unknown */
} ScalarArrayOpExpr;
/*
* BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
*
* Notice the arguments are given as a List. For NOT, of course the list
* must always have exactly one element. For AND and OR, there can be two
* or more arguments.
*/
typedef enum BoolExprType
{
AND_EXPR, OR_EXPR, NOT_EXPR
} BoolExprType;
typedef struct BoolExpr
{
Expr xpr;
BoolExprType boolop;
List *args; /* arguments to this expression */
int location; /* token location, or -1 if unknown */
} BoolExpr;
/*
* SubLink
*
* A SubLink represents a subselect appearing in an expression, and in some
* cases also the combining operator(s) just above it. The subLinkType
* indicates the form of the expression represented:
* EXISTS_SUBLINK EXISTS(SELECT ...)
* ALL_SUBLINK (lefthand) op ALL (SELECT ...)
* ANY_SUBLINK (lefthand) op ANY (SELECT ...)
* ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...)
* EXPR_SUBLINK (SELECT with single targetlist item ...)
* MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...)
* ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...)
* CTE_SUBLINK WITH query (never actually part of an expression)
* For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
* same length as the subselect's targetlist. ROWCOMPARE will *always* have
* a list with more than one entry; if the subselect has just one target
* then the parser will create an EXPR_SUBLINK instead (and any operator
* above the subselect will be represented separately).
* ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most
* one row (if it returns no rows, the result is NULL).
* ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
* results. ALL and ANY combine the per-row results using AND and OR
* semantics respectively.
* ARRAY requires just one target column, and creates an array of the target
* column's type using any number of rows resulting from the subselect.
*
* SubLink is classed as an Expr node, but it is not actually executable;
* it must be replaced in the expression tree by a SubPlan node during
* planning.
*
* NOTE: in the raw output of gram.y, testexpr contains just the raw form
* of the lefthand expression (if any), and operName is the String name of
* the combining operator. Also, subselect is a raw parsetree. During parse
* analysis, the parser transforms testexpr into a complete boolean expression
* that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
* output columns of the subselect. And subselect is transformed to a Query.
* This is the representation seen in saved rules and in the rewriter.
*
* In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName
* are unused and are always null.
*
* subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in
* other SubLinks. This number identifies different multiple-assignment
* subqueries within an UPDATE statement's SET list. It is unique only
* within a particular targetlist. The output column(s) of the MULTIEXPR
* are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist.
*
* The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used
* in SubPlans generated for WITH subqueries.
*/
typedef enum SubLinkType
{
EXISTS_SUBLINK,
ALL_SUBLINK,
ANY_SUBLINK,
ROWCOMPARE_SUBLINK,
EXPR_SUBLINK,
MULTIEXPR_SUBLINK,
ARRAY_SUBLINK,
CTE_SUBLINK /* for SubPlans only */
} SubLinkType;
typedef struct SubLink
{
Expr xpr;
SubLinkType subLinkType; /* see above */
int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */
Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */
List *operName; /* originally specified operator name */
Node *subselect; /* subselect as Query* or raw parsetree */
int location; /* token location, or -1 if unknown */
} SubLink;
/*
* SubPlan - executable expression node for a subplan (sub-SELECT)
*
* The planner replaces SubLink nodes in expression trees with SubPlan
* nodes after it has finished planning the subquery. SubPlan references
* a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
* (We avoid a direct link to make it easier to copy expression trees
* without causing multiple processing of the subplan.)
*
* In an ordinary subplan, testexpr points to an executable expression
* (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
* operator(s); the left-hand arguments are the original lefthand expressions,
* and the right-hand arguments are PARAM_EXEC Param nodes representing the
* outputs of the sub-select. (NOTE: runtime coercion functions may be
* inserted as well.) This is just the same expression tree as testexpr in
* the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
* suitably numbered PARAM_EXEC nodes.
*
* If the sub-select becomes an initplan rather than a subplan, the executable
* expression is part of the outer plan's expression tree (and the SubPlan
* node itself is not, but rather is found in the outer plan's initPlan
* list). In this case testexpr is NULL to avoid duplication.
*
* The planner also derives lists of the values that need to be passed into
* and out of the subplan. Input values are represented as a list "args" of
* expressions to be evaluated in the outer-query context (currently these
* args are always just Vars, but in principle they could be any expression).
* The values are assigned to the global PARAM_EXEC params indexed by parParam
* (the parParam and args lists must have the same ordering). setParam is a
* list of the PARAM_EXEC params that are computed by the sub-select, if it
* is an initplan; they are listed in order by sub-select output column
* position. (parParam and setParam are integer Lists, not Bitmapsets,
* because their ordering is significant.)
*
* Also, the planner computes startup and per-call costs for use of the
* SubPlan. Note that these include the cost of the subquery proper,
* evaluation of the testexpr if any, and any hashtable management overhead.
*/
typedef struct SubPlan
{
Expr xpr;
/* Fields copied from original SubLink: */
SubLinkType subLinkType; /* see above */
/* The combining operators, transformed to an executable expression: */
Node *testexpr; /* OpExpr or RowCompareExpr expression tree */
List *paramIds; /* IDs of Params embedded in the above */
/* Identification of the Plan tree to use: */
int plan_id; /* Index (from 1) in PlannedStmt.subplans */
/* Identification of the SubPlan for EXPLAIN and debugging purposes: */
char *plan_name; /* A name assigned during planning */
/* Extra data useful for determining subplan's output type: */
Oid firstColType; /* Type of first column of subplan result */
int32 firstColTypmod; /* Typmod of first column of subplan result */
Oid firstColCollation; /* Collation of first column of
* subplan result */
/* Information about execution strategy: */
bool useHashTable; /* TRUE to store subselect output in a hash
* table (implies we are doing "IN") */
bool unknownEqFalse; /* TRUE if it's okay to return FALSE when the
* spec result is UNKNOWN; this allows much
* simpler handling of null values */
/* Information for passing params into and out of the subselect: */
/* setParam and parParam are lists of integers (param IDs) */
List *setParam; /* initplan subqueries have to set these
* Params for parent plan */
List *parParam; /* indices of input Params from parent plan */
List *args; /* exprs to pass as parParam values */
/* Estimated execution costs: */
Cost startup_cost; /* one-time setup cost */
Cost per_call_cost; /* cost for each subplan evaluation */
} SubPlan;
/*
* AlternativeSubPlan - expression node for a choice among SubPlans
*
* The subplans are given as a List so that the node definition need not
* change if there's ever more than two alternatives. For the moment,
* though, there are always exactly two; and the first one is the fast-start
* plan.
*/
typedef struct AlternativeSubPlan
{
Expr xpr;
List *subplans; /* SubPlan(s) with equivalent results */
} AlternativeSubPlan;
/* ----------------
* FieldSelect
*
* FieldSelect represents the operation of extracting one field from a tuple
* value. At runtime, the input expression is expected to yield a rowtype
* Datum. The specified field number is extracted and returned as a Datum.
* ----------------
*/
typedef struct FieldSelect
{
Expr xpr;
Expr *arg; /* input expression */
AttrNumber fieldnum; /* attribute number of field to extract */
Oid resulttype; /* type of the field (result type of this
* node) */
int32 resulttypmod; /* output typmod (usually -1) */
Oid resultcollid; /* OID of collation of the field */
} FieldSelect;
/* ----------------
* FieldStore
*
* FieldStore represents the operation of modifying one field in a tuple
* value, yielding a new tuple value (the input is not touched!). Like
* the assign case of ArrayRef, this is used to implement UPDATE of a
* portion of a column.
*
* A single FieldStore can actually represent updates of several different
* fields. The parser only generates FieldStores with single-element lists,
* but the planner will collapse multiple updates of the same base column
* into one FieldStore.
* ----------------
*/
typedef struct FieldStore
{
Expr xpr;
Expr *arg; /* input tuple value */
List *newvals; /* new value(s) for field(s) */
List *fieldnums; /* integer list of field attnums */
Oid resulttype; /* type of result (same as type of arg) */
/* Like RowExpr, we deliberately omit a typmod and collation here */
} FieldStore;
/* ----------------
* RelabelType
*
* RelabelType represents a "dummy" type coercion between two binary-
* compatible datatypes, such as reinterpreting the result of an OID
* expression as an int4. It is a no-op at runtime; we only need it
* to provide a place to store the correct type to be attributed to
* the expression result during type resolution. (We can't get away
* with just overwriting the type field of the input expression node,
* so we need a separate node to show the coercion's result type.)
* ----------------
*/
typedef struct RelabelType
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type of coercion expression */
int32 resulttypmod; /* output typmod (usually -1) */
Oid resultcollid; /* OID of collation, or InvalidOid if none */
CoercionForm relabelformat; /* how to display this node */
int location; /* token location, or -1 if unknown */
} RelabelType;
/* ----------------
* CoerceViaIO
*
* CoerceViaIO represents a type coercion between two types whose textual
* representations are compatible, implemented by invoking the source type's
* typoutput function then the destination type's typinput function.
* ----------------
*/
typedef struct CoerceViaIO
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type of coercion */
/* output typmod is not stored, but is presumed -1 */
Oid resultcollid; /* OID of collation, or InvalidOid if none */
CoercionForm coerceformat; /* how to display this node */
int location; /* token location, or -1 if unknown */
} CoerceViaIO;
/* ----------------
* ArrayCoerceExpr
*
* ArrayCoerceExpr represents a type coercion from one array type to another,
* which is implemented by applying the indicated element-type coercion
* function to each element of the source array. If elemfuncid is InvalidOid
* then the element types are binary-compatible, but the coercion still
* requires some effort (we have to fix the element type ID stored in the
* array header).
* ----------------
*/
typedef struct ArrayCoerceExpr
{
Expr xpr;
Expr *arg; /* input expression (yields an array) */
Oid elemfuncid; /* OID of element coercion function, or 0 */
Oid resulttype; /* output type of coercion (an array type) */
int32 resulttypmod; /* output typmod (also element typmod) */
Oid resultcollid; /* OID of collation, or InvalidOid if none */
bool isExplicit; /* conversion semantics flag to pass to func */
CoercionForm coerceformat; /* how to display this node */
int location; /* token location, or -1 if unknown */
} ArrayCoerceExpr;
/* ----------------
* ConvertRowtypeExpr
*
* ConvertRowtypeExpr represents a type coercion from one composite type
* to another, where the source type is guaranteed to contain all the columns
* needed for the destination type plus possibly others; the columns need not
* be in the same positions, but are matched up by name. This is primarily
* used to convert a whole-row value of an inheritance child table into a
* valid whole-row value of its parent table's rowtype.
* ----------------
*/
typedef struct ConvertRowtypeExpr
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* output type (always a composite type) */
/* Like RowExpr, we deliberately omit a typmod and collation here */
CoercionForm convertformat; /* how to display this node */
int location; /* token location, or -1 if unknown */
} ConvertRowtypeExpr;
/*----------
* CollateExpr - COLLATE
*
* The planner replaces CollateExpr with RelabelType during expression
* preprocessing, so execution never sees a CollateExpr.
*----------
*/
typedef struct CollateExpr
{
Expr xpr;
Expr *arg; /* input expression */
Oid collOid; /* collation's OID */
int location; /* token location, or -1 if unknown */
} CollateExpr;
/*----------
* CaseExpr - a CASE expression
*
* We support two distinct forms of CASE expression:
* CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
* CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
* These are distinguishable by the "arg" field being NULL in the first case
* and the testexpr in the second case.
*
* In the raw grammar output for the second form, the condition expressions
* of the WHEN clauses are just the comparison values. Parse analysis
* converts these to valid boolean expressions of the form
* CaseTestExpr '=' compexpr
* where the CaseTestExpr node is a placeholder that emits the correct
* value at runtime. This structure is used so that the testexpr need be
* evaluated only once. Note that after parse analysis, the condition
* expressions always yield boolean.
*
* Note: we can test whether a CaseExpr has been through parse analysis
* yet by checking whether casetype is InvalidOid or not.
*----------
*/
typedef struct CaseExpr
{
Expr xpr;
Oid casetype; /* type of expression result */
Oid casecollid; /* OID of collation, or InvalidOid if none */
Expr *arg; /* implicit equality comparison argument */
List *args; /* the arguments (list of WHEN clauses) */
Expr *defresult; /* the default result (ELSE clause) */
int location; /* token location, or -1 if unknown */
} CaseExpr;
/*
* CaseWhen - one arm of a CASE expression
*/
typedef struct CaseWhen
{
Expr xpr;
Expr *expr; /* condition expression */
Expr *result; /* substitution result */
int location; /* token location, or -1 if unknown */
} CaseWhen;
/*
* Placeholder node for the test value to be processed by a CASE expression.
* This is effectively like a Param, but can be implemented more simply
* since we need only one replacement value at a time.
*
* We also use this in nested UPDATE expressions.
* See transformAssignmentIndirection().
*/
typedef struct CaseTestExpr
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
Oid collation; /* collation for the substituted value */
} CaseTestExpr;
/*
* ArrayExpr - an ARRAY[] expression
*
* Note: if multidims is false, the constituent expressions all yield the
* scalar type identified by element_typeid. If multidims is true, the
* constituent expressions all yield arrays of element_typeid (ie, the same
* type as array_typeid); at runtime we must check for compatible subscripts.
*/
typedef struct ArrayExpr
{
Expr xpr;
Oid array_typeid; /* type of expression result */
Oid array_collid; /* OID of collation, or InvalidOid if none */
Oid element_typeid; /* common type of array elements */
List *elements; /* the array elements or sub-arrays */
bool multidims; /* true if elements are sub-arrays */
int location; /* token location, or -1 if unknown */
} ArrayExpr;
/*
* RowExpr - a ROW() expression
*
* Note: the list of fields must have a one-for-one correspondence with
* physical fields of the associated rowtype, although it is okay for it
* to be shorter than the rowtype. That is, the N'th list element must
* match up with the N'th physical field. When the N'th physical field
* is a dropped column (attisdropped) then the N'th list element can just
* be a NULL constant. (This case can only occur for named composite types,
* not RECORD types, since those are built from the RowExpr itself rather
* than vice versa.) It is important not to assume that length(args) is
* the same as the number of columns logically present in the rowtype.
*
* colnames provides field names in cases where the names can't easily be
* obtained otherwise. Names *must* be provided if row_typeid is RECORDOID.
* If row_typeid identifies a known composite type, colnames can be NIL to
* indicate the type's cataloged field names apply. Note that colnames can
* be non-NIL even for a composite type, and typically is when the RowExpr
* was created by expanding a whole-row Var. This is so that we can retain
* the column alias names of the RTE that the Var referenced (which would
* otherwise be very difficult to extract from the parsetree). Like the
* args list, colnames is one-for-one with physical fields of the rowtype.
*/
typedef struct RowExpr
{
Expr xpr;
List *args; /* the fields */
Oid row_typeid; /* RECORDOID or a composite type's ID */
/*
* Note: we deliberately do NOT store a typmod. Although a typmod will be
* associated with specific RECORD types at runtime, it will differ for
* different backends, and so cannot safely be stored in stored
* parsetrees. We must assume typmod -1 for a RowExpr node.
*
* We don't need to store a collation either. The result type is
* necessarily composite, and composite types never have a collation.
*/
CoercionForm row_format; /* how to display this node */
List *colnames; /* list of String, or NIL */
int location; /* token location, or -1 if unknown */
} RowExpr;
/*
* RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
*
* We support row comparison for any operator that can be determined to
* act like =, <>, <, <=, >, or >= (we determine this by looking for the
* operator in btree opfamilies). Note that the same operator name might
* map to a different operator for each pair of row elements, since the
* element datatypes can vary.
*
* A RowCompareExpr node is only generated for the < <= > >= cases;
* the = and <> cases are translated to simple AND or OR combinations
* of the pairwise comparisons. However, we include = and <> in the
* RowCompareType enum for the convenience of parser logic.
*/
typedef enum RowCompareType
{
/* Values of this enum are chosen to match btree strategy numbers */
ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
ROWCOMPARE_NE = 6 /* no such btree strategy */
} RowCompareType;
typedef struct RowCompareExpr
{
Expr xpr;
RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
List *opnos; /* OID list of pairwise comparison ops */
List *opfamilies; /* OID list of containing operator families */
List *inputcollids; /* OID list of collations for comparisons */
List *largs; /* the left-hand input arguments */
List *rargs; /* the right-hand input arguments */
} RowCompareExpr;
/*
* CoalesceExpr - a COALESCE expression
*/
typedef struct CoalesceExpr
{
Expr xpr;
Oid coalescetype; /* type of expression result */
Oid coalescecollid; /* OID of collation, or InvalidOid if none */
List *args; /* the arguments */
int location; /* token location, or -1 if unknown */
} CoalesceExpr;
/*
* MinMaxExpr - a GREATEST or LEAST function
*/
typedef enum MinMaxOp
{
IS_GREATEST,
IS_LEAST
} MinMaxOp;
typedef struct MinMaxExpr
{
Expr xpr;
Oid minmaxtype; /* common type of arguments and result */
Oid minmaxcollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that function should use */
MinMaxOp op; /* function to execute */
List *args; /* the arguments */
int location; /* token location, or -1 if unknown */
} MinMaxExpr;
/*
* XmlExpr - various SQL/XML functions requiring special grammar productions
*
* 'name' carries the "NAME foo" argument (already XML-escaped).
* 'named_args' and 'arg_names' represent an xml_attribute list.
* 'args' carries all other arguments.
*
* Note: result type/typmod/collation are not stored, but can be deduced
* from the XmlExprOp. The type/typmod fields are just used for display
* purposes, and are NOT necessarily the true result type of the node.
*/
typedef enum XmlExprOp
{
IS_XMLCONCAT, /* XMLCONCAT(args) */
IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */
IS_XMLFOREST, /* XMLFOREST(xml_attributes) */
IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */
IS_XMLPI, /* XMLPI(name [, args]) */
IS_XMLROOT, /* XMLROOT(xml, version, standalone) */
IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
IS_DOCUMENT /* xmlval IS DOCUMENT */
} XmlExprOp;
typedef enum
{
XMLOPTION_DOCUMENT,
XMLOPTION_CONTENT
} XmlOptionType;
typedef struct XmlExpr
{
Expr xpr;
XmlExprOp op; /* xml function ID */
char *name; /* name in xml(NAME foo ...) syntaxes */
List *named_args; /* non-XML expressions for xml_attributes */
List *arg_names; /* parallel list of Value strings */
List *args; /* list of expressions */
XmlOptionType xmloption; /* DOCUMENT or CONTENT */
Oid type; /* target type/typmod for XMLSERIALIZE */
int32 typmod;
int location; /* token location, or -1 if unknown */
} XmlExpr;
/* ----------------
* NullTest
*
* NullTest represents the operation of testing a value for NULLness.
* The appropriate test is performed and returned as a boolean Datum.
*
* When argisrow is false, this simply represents a test for the null value.
*
* When argisrow is true, the input expression must yield a rowtype, and
* the node implements "row IS [NOT] NULL" per the SQL standard. This
* includes checking individual fields for NULLness when the row datum
* itself isn't NULL.
*
* NOTE: the combination of a rowtype input and argisrow==false does NOT
* correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
* represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
* ----------------
*/
typedef enum NullTestType
{
IS_NULL, IS_NOT_NULL
} NullTestType;
typedef struct NullTest
{
Expr xpr;
Expr *arg; /* input expression */
NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
bool argisrow; /* T to perform field-by-field null checks */
int location; /* token location, or -1 if unknown */
} NullTest;
/*
* BooleanTest
*
* BooleanTest represents the operation of determining whether a boolean
* is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
* are supported. Note that a NULL input does *not* cause a NULL result.
* The appropriate test is performed and returned as a boolean Datum.
*/
typedef enum BoolTestType
{
IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
} BoolTestType;
typedef struct BooleanTest
{
Expr xpr;
Expr *arg; /* input expression */
BoolTestType booltesttype; /* test type */
int location; /* token location, or -1 if unknown */
} BooleanTest;
/*
* CoerceToDomain
*
* CoerceToDomain represents the operation of coercing a value to a domain
* type. At runtime (and not before) the precise set of constraints to be
* checked will be determined. If the value passes, it is returned as the
* result; if not, an error is raised. Note that this is equivalent to
* RelabelType in the scenario where no constraints are applied.
*/
typedef struct CoerceToDomain
{
Expr xpr;
Expr *arg; /* input expression */
Oid resulttype; /* domain type ID (result type) */
int32 resulttypmod; /* output typmod (currently always -1) */
Oid resultcollid; /* OID of collation, or InvalidOid if none */
CoercionForm coercionformat; /* how to display this node */
int location; /* token location, or -1 if unknown */
} CoerceToDomain;
/*
* Placeholder node for the value to be processed by a domain's check
* constraint. This is effectively like a Param, but can be implemented more
* simply since we need only one replacement value at a time.
*
* Note: the typeId/typeMod/collation will be set from the domain's base type,
* not the domain itself. This is because we shouldn't consider the value
* to be a member of the domain if we haven't yet checked its constraints.
*/
typedef struct CoerceToDomainValue
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
Oid collation; /* collation for the substituted value */
int location; /* token location, or -1 if unknown */
} CoerceToDomainValue;
/*
* Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
*
* This is not an executable expression: it must be replaced by the actual
* column default expression during rewriting. But it is convenient to
* treat it as an expression node during parsing and rewriting.
*/
typedef struct SetToDefault
{
Expr xpr;
Oid typeId; /* type for substituted value */
int32 typeMod; /* typemod for substituted value */
Oid collation; /* collation for the substituted value */
int location; /* token location, or -1 if unknown */
} SetToDefault;
/*
* Node representing [WHERE] CURRENT OF cursor_name
*
* CURRENT OF is a bit like a Var, in that it carries the rangetable index
* of the target relation being constrained; this aids placing the expression
* correctly during planning. We can assume however that its "levelsup" is
* always zero, due to the syntactic constraints on where it can appear.
*
* The referenced cursor can be represented either as a hardwired string
* or as a reference to a run-time parameter of type REFCURSOR. The latter
* case is for the convenience of plpgsql.
*/
typedef struct CurrentOfExpr
{
Expr xpr;
Index cvarno; /* RT index of target relation */
char *cursor_name; /* name of referenced cursor, or NULL */
int cursor_param; /* refcursor parameter number, or 0 */
} CurrentOfExpr;
/*
* InferenceElem - an element of a unique index inference specification
*
* This mostly matches the structure of IndexElems, but having a dedicated
* primnode allows for a clean separation between the use of index parameters
* by utility commands, and this node.
*/
typedef struct InferenceElem
{
Expr xpr;
Node *expr; /* expression to infer from, or NULL */
Oid infercollid; /* OID of collation, or InvalidOid */
Oid inferopclass; /* OID of att opclass, or InvalidOid */
} InferenceElem;
/*--------------------
* TargetEntry -
* a target entry (used in query target lists)
*
* Strictly speaking, a TargetEntry isn't an expression node (since it can't
* be evaluated by ExecEvalExpr). But we treat it as one anyway, since in
* very many places it's convenient to process a whole query targetlist as a
* single expression tree.
*
* In a SELECT's targetlist, resno should always be equal to the item's
* ordinal position (counting from 1). However, in an INSERT or UPDATE
* targetlist, resno represents the attribute number of the destination
* column for the item; so there may be missing or out-of-order resnos.
* It is even legal to have duplicated resnos; consider
* UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
* The two meanings come together in the executor, because the planner
* transforms INSERT/UPDATE tlists into a normalized form with exactly
* one entry for each column of the destination table. Before that's
* happened, however, it is risky to assume that resno == position.
* Generally get_tle_by_resno() should be used rather than list_nth()
* to fetch tlist entries by resno, and only in SELECT should you assume
* that resno is a unique identifier.
*
* resname is required to represent the correct column name in non-resjunk
* entries of top-level SELECT targetlists, since it will be used as the
* column title sent to the frontend. In most other contexts it is only
* a debugging aid, and may be wrong or even NULL. (In particular, it may
* be wrong in a tlist from a stored rule, if the referenced column has been
* renamed by ALTER TABLE since the rule was made. Also, the planner tends
* to store NULL rather than look up a valid name for tlist entries in
* non-toplevel plan nodes.) In resjunk entries, resname should be either
* a specific system-generated name (such as "ctid") or NULL; anything else
* risks confusing ExecGetJunkAttribute!
*
* ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
* DISTINCT items. Targetlist entries with ressortgroupref=0 are not
* sort/group items. If ressortgroupref>0, then this item is an ORDER BY,
* GROUP BY, and/or DISTINCT target value. No two entries in a targetlist
* may have the same nonzero ressortgroupref --- but there is no particular
* meaning to the nonzero values, except as tags. (For example, one must
* not assume that lower ressortgroupref means a more significant sort key.)
* The order of the associated SortGroupClause lists determine the semantics.
*
* resorigtbl/resorigcol identify the source of the column, if it is a
* simple reference to a column of a base table (or view). If it is not
* a simple reference, these fields are zeroes.
*
* If resjunk is true then the column is a working column (such as a sort key)
* that should be removed from the final output of the query. Resjunk columns
* must have resnos that cannot duplicate any regular column's resno. Also
* note that there are places that assume resjunk columns come after non-junk
* columns.
*--------------------
*/
typedef struct TargetEntry
{
Expr xpr;
Expr *expr; /* expression to evaluate */
AttrNumber resno; /* attribute number (see notes above) */
char *resname; /* name of the column (could be NULL) */
Index ressortgroupref;/* nonzero if referenced by a sort/group
* clause */
Oid resorigtbl; /* OID of column's source table */
AttrNumber resorigcol; /* column's number in source table */
bool resjunk; /* set to true to eliminate the attribute from
* final target list */
} TargetEntry;
/* ----------------------------------------------------------------
* node types for join trees
*
* The leaves of a join tree structure are RangeTblRef nodes. Above
* these, JoinExpr nodes can appear to denote a specific kind of join
* or qualified join. Also, FromExpr nodes can appear to denote an
* ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
* FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
* may have any number of child nodes, not just two.
*
* NOTE: the top level of a Query's jointree is always a FromExpr.
* Even if the jointree contains no rels, there will be a FromExpr.
*
* NOTE: the qualification expressions present in JoinExpr nodes are
* *in addition to* the query's main WHERE clause, which appears as the
* qual of the top-level FromExpr. The reason for associating quals with
* specific nodes in the jointree is that the position of a qual is critical
* when outer joins are present. (If we enforce a qual too soon or too late,
* that may cause the outer join to produce the wrong set of NULL-extended
* rows.) If all joins are inner joins then all the qual positions are
* semantically interchangeable.
*
* NOTE: in the raw output of gram.y, a join tree contains RangeVar,
* RangeSubselect, and RangeFunction nodes, which are all replaced by
* RangeTblRef nodes during the parse analysis phase. Also, the top-level
* FromExpr is added during parse analysis; the grammar regards FROM and
* WHERE as separate.
* ----------------------------------------------------------------
*/
/*
* RangeTblRef - reference to an entry in the query's rangetable
*
* We could use direct pointers to the RT entries and skip having these
* nodes, but multiple pointers to the same node in a querytree cause
* lots of headaches, so it seems better to store an index into the RT.
*/
typedef struct RangeTblRef
{
NodeTag type;
int rtindex;
} RangeTblRef;
/*----------
* JoinExpr - for SQL JOIN expressions
*
* isNatural, usingClause, and quals are interdependent. The user can write
* only one of NATURAL, USING(), or ON() (this is enforced by the grammar).
* If he writes NATURAL then parse analysis generates the equivalent USING()
* list, and from that fills in "quals" with the right equality comparisons.
* If he writes USING() then "quals" is filled with equality comparisons.
* If he writes ON() then only "quals" is set. Note that NATURAL/USING
* are not equivalent to ON() since they also affect the output column list.
*
* alias is an Alias node representing the AS alias-clause attached to the
* join expression, or NULL if no clause. NB: presence or absence of the
* alias has a critical impact on semantics, because a join with an alias
* restricts visibility of the tables/columns inside it.
*
* During parse analysis, an RTE is created for the Join, and its index
* is filled into rtindex. This RTE is present mainly so that Vars can
* be created that refer to the outputs of the join. The planner sometimes
* generates JoinExprs internally; these can have rtindex = 0 if there are
* no join alias variables referencing such joins.
*----------
*/
typedef struct JoinExpr
{
NodeTag type;
JoinType jointype; /* type of join */
bool isNatural; /* Natural join? Will need to shape table */
Node *larg; /* left subtree */
Node *rarg; /* right subtree */
List *usingClause; /* USING clause, if any (list of String) */
Node *quals; /* qualifiers on join, if any */
Alias *alias; /* user-written alias clause, if any */
int rtindex; /* RT index assigned for join, or 0 */
} JoinExpr;
/*----------
* FromExpr - represents a FROM ... WHERE ... construct
*
* This is both more flexible than a JoinExpr (it can have any number of
* children, including zero) and less so --- we don't need to deal with
* aliases and so on. The output column set is implicitly just the union
* of the outputs of the children.
*----------
*/
typedef struct FromExpr
{
NodeTag type;
List *fromlist; /* List of join subtrees */
Node *quals; /* qualifiers on join, if any */
} FromExpr;
/*----------
* OnConflictExpr - represents an ON CONFLICT DO ... expression
*
* The optimizer requires a list of inference elements, and optionally a WHERE
* clause to infer a unique index. The unique index (or, occasionally,
* indexes) inferred are used to arbitrate whether or not the alternative ON
* CONFLICT path is taken.
*----------
*/
typedef struct OnConflictExpr
{
NodeTag type;
OnConflictAction action; /* DO NOTHING or UPDATE? */
/* Arbiter */
List *arbiterElems; /* unique index arbiter list (of
* InferenceElem's) */
Node *arbiterWhere; /* unique index arbiter WHERE clause */
Oid constraint; /* pg_constraint OID for arbiter */
/* ON CONFLICT UPDATE */
List *onConflictSet; /* List of ON CONFLICT SET TargetEntrys */
Node *onConflictWhere; /* qualifiers to restrict UPDATE to */
int exclRelIndex; /* RT index of 'excluded' relation */
List *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */
} OnConflictExpr;
#endif /* PRIMNODES_H */
|